«i WfYPB'H &&rt

§4 ™ *»' *• *»*•'• O0i

the signal is started from P» «nn«iv«t«i by ^ and again pc*rcei?©d at
p, we ht*Y0 by (2H4) for th«* abnolutt* coordinates of tho points
where the Bjgnal m found nt thi'm

0, 0, 0; * -4- «''n *A /; «%• 0, 0,

mi iiaoe th* diHtanM from th** first t*» th«* wwund is tr»Y«Ued over
in an interval li? nud that from th« wn-oad tt» thtt third m «n iator-

By mwtnii of tht»m* 0tjuntion« lt and ls can

•,. howi^ffir, tt» fsonniditr thn quantities

Indttd, th§ fonuuliM) mwy ttn it«n5ii»r{tt«»d to
,t/s 'I y* t /* — rVl*
/» f »/» t /'-c-Vf*

Hut it aittwartt fr»*in t*{nwtii«i ii*Hrt* f^r witirli wt mav nt*w writ*

that tin* vnriabln fff «lpfifsn*ii by <//*«! i« tii

timt* of 1* timt Ua* t»k|»i»»iil tmiwi»n tin* dturiwig wti! thi* rtftuni »f lhi»
idgnal On thi» «th»*r twiiil, l^r** -I- ,f(* f /* if lit** hmgth I* which

tH*« to th« I* if, anti ' / it tit*

th« wdodty «f Itglit wliirli liw fl««4«i**?i from tip l«|ii»tbia

^) iliowit that tins tiiltp* will bi* «ttiikt l«i f,

« ^2fil It w trnfftctmifc t«» «b«rrr« tlwt, m » m»wi from

^ it eluufe ttM l«f«I of V will »nrk tin*

I/ at th« ^ ii bj tho

tceosrding to (jKJl), thin ft* if in the text.